Would appreciate any help on this, 98 e320, wanted to know how to adjust idle up just a tad. It idles rough with AC on. Does not adjust up automatically when turning on AC. From reading others on here and web, may be transmission mounts. Apparently no way to just turn a screw and bump it up about 500 RPM. So is it my mounts or some sensor or module? Thanks pete

 

the dealer can bump your idle, but you need to fix the issue. probably need a tune up. also dont run regular fuel. motor mounts might help, but take care of the engine smooth running issue first.

 

Thank you very muck for taking time to respond. My car only has 85k on it and I do let dealer work on it. I will call first. Usually I prepare for cost but it always seems to be 3 or 4 hundred dollars more than expected. Thanks Again Pete